.\" -*- nroff -*-
.\" Copyright 2010 Cisco Systems, Inc.  All rights reserved.
.\" Copyright 2006-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines Corporation
.\" $COPYRIGHT$
.TH MPI_Graph_neighbors_count 3 "Jun 10, 2020" "4.0.4" "Open MPI"
.SH NAME
\fBMPI_Graph_neighbors_count \fP \- Returns the number of neighbors of a node associated with a graph topology.

.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Graph_neighbors_count(MPI_Comm \fIcomm\fP, int\fI rank\fP,
	int\fI *nneighbors\fP)

.fi
.SH INPUT PARAMETERS
.ft R
.TP 1i
comm
Communicator with graph topology (handle).
.TP 1i
rank
Rank of process in group of comm (integer).

.SH OUTPUT PARAMETERS
.ft R
.TP 1i
nneighbors
Number of neighbors of specified process (integer).
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer).

.SH DESCRIPTION
.ft R
MPI_Graph_neighbors_count and MPI_Graph_neighbors provide adjacency information for a general, graph topology. MPI_Graph_neighbors_count returns the number of neighbors for the process signified by rank.

.SH ERRORS
Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI::Exception object.
.sp
Before the error value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

.SH SEE ALSO
.ft R
.sp
MPI_Graph_neighbors

